"It is an honour for all of our city's residents to see Vancouver recognized with this important award at the COP21 UN Climage Change Summit, as we build upon our work together to confront climate change and make Vancouver the greenest city in the world," Robertson said in a news release.

In its latest update on the plan, the city reported that greenhouse-gas emissions in Vancouver are down seven percent since 2007. The plan aims to reduce emissions by 33 percent below 2007 levels by 2020.

The Greenest City Action Plan also requires all buildings constructed from 2020 forward to be carbon-neutral in their operations. Emissions from residential and commercial buildings are down five percent since 2007.

Another target is to make more than 50 percent of trips by bike, walking, or transit by 2020. That objective was reached by April of this year.

The cochairs of the Greenest City Action Team are Mayor Gregor Robertson and environmental lawyer and author David Boyd.

Boyd's recent book, The Optimistic Environmentalist, maintained that there's an "enduring myth that society must choose between environmental protection and economic well-being".

"This myth has been debunked by piles of academic studies, and more importantly by the experiences of communities, companies, and countries around the world," Boyd writes. "From Norway and Germany to Costa Rica and Brazil, from Vancouver to Stockholm, and from Alter Ego to Tesla, there is compelling evidence that the benefits of protecting the environment dwarfs the costs."